Feed carriage control mechanism



T. H. LJUNGGREN ET AL A A FEED CARRIAGE CONTROL MECHANISM Filed Oct.1946 5 Shets-Sheec. i

N V T Q ill- Inveniors TEN? H Ljunugren LUiiiis F Mame W456 wwwmg 195 9"r. H. LJUNGGREN ET AL y fi FEED CARRIAGE CONTROL MECHANISM Filed Oct.4; 1946 Invmmrs Tim" Hl iungr mn films F. Mama At'h s 11 7 19% H.LJUNGGREN ET AL 24954@@ FEED CARRIAGE CONTROL MECHANISM Filed Oct. 4,1946 s Sheets-Sheet 5 The?" H. Li ungfl w MM Ms F Mmm Patented Feb. 7,1950 UNITED STATES PATENT OFFICE 2,495,400 FEED CARRIAGE CONTROLMECHANISM Vermont Application October 4, 1946, Serial No. 701,230 6Claims. (01. 51-165) This invention relates to carriage feed mechanismby which devices such as electric switches may be actuated to produce acycle change in the feed of the carriage, whenever the carriage reachesone or more predetermined feed positions, and has for one object toprovide a construction which permits ready adjustment of the deviceactuating elements to accurate predetermined carriage positions andafter accurate predetermined extents of feed from starting positions.

More particularly the invention relates to control of carriage feedmechanism for grinding machines in which the grinding wheel and the workare moved toward each other from a retracted relation at a rapid rateuntil they are near together but still out of contact, whereupon therate of feed is reduced to a rate suitable for grinding feed, contactbetween the work and the wheel being effected while the feed is at thelow rate. The grinding action may be divided into two phases, the firstbeing rough grinding at a low rate, reducing the work to a size short offinished size, and the second, a finish grinding which completes thefinal sizing operation at a feed rate usually slower than the roughgrinding rate, the wheel and the work being fully retracted betweenrough and finish grinding and after finish grinding. The rapid idle feedfrom the retracted position toward wheel and work contact may thereforebe longer for finish grinding than for rough grinding because of theamount of work removed during the rough. grinding. The extent of rapidfeed for rough and finish grinding is therefore independently adjustablein accordance with this invention.

For a complete understanding of this invention, reference may be had tothe accompanying drawings in which Figure 1 is a fragmentary frontelevation of a grinding machine embodying the invention Figure 2 is adetail sectional View to a larger scale on line 2-2 of Figure 1.

Figure 3 is a fragmentary view partly in side elevation and partly incentral vertical section through the carriage feed mechanism.

Figure 4 is a detail sectional view on line 44 of Figure 2.

Figure 5 is a diagrammatic view of the work and grinding wheel showingdiagrammatically the amount of stock removed in the rough and finishgrinding portions of the cycle and the relative positions of thegrinding wheel and work at which. the change from rapid idle feed toslow working feed takes place.

Figure 6 is a diagrammatic view of the feed mechanism and controls.

Referring to the drawings, at I is indicated a carriage which maysupport a work piece or a grinding wheel, or other tool, a grindingwheel being so shown in Figure 6 and the work holder being shown at 9 inFigure 5. This carriage has iournaled therein a lead screw 3 threadedinto a nut 2 which is journaled in a, fixed portion of the machineframe. The nut 2 has fixed thereto a gear 4 with which meshes a gear 5on a shaft 6. This gear 5 may have integral therewith a second gear Iwith which meshes a rack bar 8. By imparting axial motion to the rackbar 8, it will be evident that the gears I and 5 may be rotated,rotating the gear 4 and the nut 2, causing the lead screw 3 and thecarriage to be moved axially of the lead screw.

Means may also be provided for rotating the lead screw with reference tothe carriage, this imparting a selective feed motion to provide forwheel wear and truing. This additional means may comprise a worm I0which may be brought into engagement with a worm wheel II carried by thelead screw 3. Also the lead screw 3 may have secured thereto, a handwheel I2 by which it may be turned when the worm I0 is lifted out ofengagement with the worm wheel I I. This means for feeding the Workcarriage comprising the lead screw and nut is a micrometric feedingmeans actuable for feeding the carriage by accurate increments.

As shown best in Figure 2, the shaft 6 may have fixed thereto a disk I5,which, as shown best in Figure 1, may be graduated around its periphery,the graduations on the 'disk coacting with a fixed reference mark IT onthe machine frame. By comparison of the scale readings on the diskopposite to the reference lin H, an accurate indication of the extent offeed motion imparted to the carriage as the disk is turned by the actionof the rack bar 8 may be readily had.

The shaft 6 has journaled thereon a pair of arms 20 and 2|. These armsmay be selectively secured at desired angular positions to thedisk I5.For this purpose they are shown as provided with thumb screws 22 and 23which extend through arcuate slots 24 and 25 through the disk I5, thesethumb screws being threaded into the arms 20 and 2|, respectively. Oneach side of the shaft 6 are arranged the electric switches 21 and 28having actuating elements 29 and 30, respectively, and these actuatingelements are arranged in the paths of motion of elements :.0f' theswitches .54, 55 and 56.

shown as segmental pieces 3| and 32 which extend between the shaft 6 andthe switch elements 29 and 30 and which at their forward ends have feet33 and 34 which are secured to the arms 2! and 20 as by screws 35. InFigure 6 the shaft carrying the arms 20 and 2| is shown geared to theshaft 6. for. the .sakeof clarityof showing and may be actually so madeif desired.

It will now be evident that as the carriage is being fed from a startingposition, which-may be assumed as that where the .zero on the disk lcomes opposite to the fixed indication ll, the arms and 2! arerotatediwith the disk until such time as one or the other of thesegments 31 and 32 contact with and actuate their respective switches.As shown, for example, the arm 20 is arranged to contactitsswitchelement after the disk has been turned twenty graduations, whereupon theswitch 28 is closed, while further turning of the Idisk another tengraduaxtions-isnecessary to close the switch 21.

In Figure 6 the mechanism is shown embodied :imagrinding machinewithcontrols-of the type -more fully setzforthin an application for patentof Thor'i-H. .Ljunggren, Serial No. 701,443 :filed October 5, 1946, forInternal grinding -machine, wherein theva'rious phases of the-grindingcycle .are controlled by; a grinding cycle control mechanism-comprisinga plurality of rotary switchactnated ,devices secured to a common shaftvwhich' isrotated step-by step to produce the de --sired: phase changeof :the cycle. A portion of this cycle control, -mechanism isillustrated in Figure 6 comprising :a shaft carrying a plu- -rality of.disks' 5l,:52, and"53, each provided at 'lPUmtSI OH its periphery withprojections which at" certain angular positions of the shaft 5% mayclose switches 54, and 56. .The rack bar 8, by motion of which the feedmechanism is operated; forms" the :piston rod of a piston '58 whichrides ina fluid-.pressurecylinder 59 having pipes and-passages 6B and.Bi communicating with its interioron opposite sides of the piston .58.:-Moti0n of the piston 58 to the left from the position of Figure5produces 'feed between the grinding wheel carried by the carriage l andthe workf66 (see Figure 5), while motion of the :piston' 58 in'theopposite direction acts to retract the wheel from the work.

Controlof fluid pressure to and from the cylinder. 59 is provided byfour valves '10, H, 72 and 13, each of which is normallyiin one axialposi- .tion, though it: may be moved to another axial position byenergizing an actuating solenoid therefor :14, 15, 16 and 11,respectively, energizing. of these solenoids beingcontrolled by closingFluid pressure .is supplied from a suitablesourcea pump being shown forthe-purposataking hydraulic fluid from a tank 8! and-delivering itunder-pressure -'determined by the setting of a relief valve 82 in .adischarge pipe83 leading back to the tank, the fluid being delivered atthe predetermined .pressureto .a pressure-pipe 85. -A'discharge pipe -86leads back to the tank 8 l Elec,tricalenergy for. energizing the varioussolenoids 14, .15, I6 and I1. is derived from the ;line--90,= this lineleading through a lead 91 to the switches-54, 55 and 56. The line alsoleads to one terminal of the switch 2'! and also communicates through alead 9| with one terrminal of a switch 92, this switch 92 being a safetyswitch. "The mechanism is. shown in Figure 6 as in its retractedposition, the pressure pipe 85 It. through the pipe 6! leading to theleft hand end of the cylinder 59, and the pipe 50 leading to the righthand end of the cylinder 59 leading past the valve H into a pipe 95communicating with the drain pipe 85.

Assuming that a piece of work is in position in the work holder 9, andthe. rough grinding operation is to be started, the shaft 50 is turnedinto the angular position to bring one of the projections on the disk 5|into position to close the switch 54,.and to bring one of theprojections on the disk 53 into position to close the switch 56. Closingof the switch 54 energizes from the lead 9i and the switch 54, a leadH35 passing to one side of the rough grinding switch 28. The closing ofthe switch 56 energizes a lead ltl which energizes the solenoids 14 and15, lifting the valve (0 and "H. Lifting oi the valve ll allowspressure'from the pipe 95 to pass the valve H into the pipe Gil leadingto the right hand end of the cylinder .58, while the lifting ofthevalve- Ill causes the pipe (ii to conduct d'mcharge pressure from theleft hand end of the cylinder-59 past the valve 'lil:and into the pipe.l02, whichrleads to the valve 12. The switch 92.being closedwvhen thefeed. carriage is in fully retracted position, energizes the lead I03and energizes the-solenoid .76 so that the. valve 12 is in-.lif-tedposition-as shown, the discharge-from thetpipe lll2then passing aroundthe valve 12 through the pipe M4 to the valve Handout through the-pipeL05 containing a' throttle waive-106 to the main-drain pipe Jillleading-back to thetank ll'l. The deed mechanism then star-ts tomove tofeeclthe-wheel toward the work, but-soonrafter this is done'the switch92opens,.allowing the valve 12- to -drop so that-discharge takesplaeefrom-the pipe. I02 through the valve-I2 into the pipe. SIG-and, thedrain pipe 36 without throttling. The feed thus after predetermined.delaying .action'of switch 32 is ata relatively rapid rate and thistakes place until the cam 32. engagesand closes .theswitch 23. Thistakes place when thegrindingwheel G5 has moved toward the workup .to the.linea shown ,in Figure 5, atwhich point it is .not quite in contactwith the work. As soon as this switch 28 is closed, the solenoid .15 isenergized .irom the lead I00 through the switchZS, leads Mtand .103,this lifting the valve 12 and causing the discharge to take placethrough pipe lMpast the valve 73, through pipe I05 and through thethrottle valve N36. The further feed between the wheel and the work upto the limit of rough grinding at the line b then takes place at therelative slow rough working feed rate. When this limit b is reached, theshaft 50 is turned a further distance so asto allow the switches 54 and56 to open, conditioning the various valves, except the valve I2, in thepositionv shown. in Figure 6, so that the carriage is retracted to itsstarting position. at which time the switch-=82 is closed, lifting thevalve 12 so that all the parts except the shaft 50 and its disks isin'the position shown in Figure 6. At this point in the cycle, the wheelmay be retracted and trued, as-is fully described in the Ljunggrenapplication to-which attention has heretofore been called, but as thisportion of the cycle is not concerned with the present invention it isnot here shown.

Thefinish grindingoperation is then initiated, thisbeing done byrotating the shaft :50 until projections on the disks 52 =and-53closethe -switches-55-and 56. Asbeforeznoted, closing of the switch'56lifts thevalves' flfl and- 1|,=thus communicating through a pipe 95,past the valve .-.75 causing the piston tube-driven in feed-direction,and assoon as the feed starts the valve 12 drops so that the feed takesplace at the rapid unrestricted rate. The closing of the switch 55energizes the lead H5 which energizes the solenoid 'l'l, lifting thevalve 13. This connects the pipe I04 past the valve 73 to the pipe I20,in which is placed the throttle valve I21, and after passing thisthrottle valve the fluid pressure flows to the discharge pipe I01. Thisthrottle valve l2! may be set to restrict the flow more than thethrottle valve I06 so that the speed of slow feed for finish grinding,as will later appear, is slower than the feed for rough grinding. Therapid rate feed continues until the cam 3| closes the switch 21, which,itwill be noted, is after the closing of the switch 28, but as duringthe finish grinding feed the lead 100 is not energized, switch 54 beingopen, nothing happens when the switch 28 is closed. When the switch 21is closed, however, energypasses from the line 90 through this switch 21and the lead I03 to the solenoid 16, which thereupon lifts the valve 12into the position shown in Figure 6, whereupon the discharge from theleft hand end of the feed cylinder 59 is compelled to go through thepipe I04, past the lifted valve 13, and through the throttle valve Hi.

It will be noted that the limit of fast feed in the finish grindingphase of the cycle may be beyond the limit of fast feed for the roughgrinding, for the reason that the stock up to the line b was removedduring the rough grinding. Limit of fast feed before the wheel cancontact the work during the finish grinding may thus be at the point e,and from this point the wheel is moved with the slow finish grindingfeed to the finish size position at d, at which point the feed isstopped by any suitable means, and the grinding operation has beencompleted.

The switch 92 has a delaying function of particular importance inconnection with certain high rate production work. This switch isnormally open, but it is held closed by the rack bar 8 when the rack baris in the retracted position of Figure 6, so that the discharge from thecylinder 59 when the feed action is started, is throttled. After a shorttravel of the rack bar 8 toward the left, the switch 92 opens and thedesired quick approach movement in transverse direction between thewheel and the work takes place. Because of the delaying action of theswitch 92, the grinding wheel and the work have had time to arrive atapproximately the relative overlapping axial positions of Figure beforethe wheel can contact with the work, so that any risk that the wheelwill bump its corner against the corner of the work piece on enteringthe work is eliminated.

It will be noted that the rough and finish grinding actions alternate sothat the switch actuating elements 3| and 32 become effectivealternately, the cycle mechanism automatically selecting alternateswitches to be effected during the feed actuations.

From the foregoing description of an embodiment of this invention, itshould be evident to those skilled in the art that various changes andmodifications may be made without departing from its spirit or scope.

We claim:

1. In combination with a movable carriage and micrometric means forfeeding said carriage including a rotary shaft turnable through anangular extent proportional to the amount of feed of said carriage froma starting position, means for turning said shaft, a pair of switcheslocated'on opposite sides of said sha'ft,-a disk fixed to said shaft, apair of arms each pivoted on said shaft, means for selectively lockingsaid arms independently to said disk in desired angular positions, andan element projecting from each of said arms between said shaft aridswitches in position to actuate said switches on feed of said carriageto positions corresponding to the angular settings of said arms relativeto said disk.

2. In combination with a movable carriage and micrometric means forfeeding said carriage including a rotary shaft turnable through anangular extent proportional to the amount of feed of said carriage froma starting position, means for turning said shaft, a pair of switchesadjacent to said shaft, a disk fixed to said shaft, a pair of arms eachpivoted on said shaft, means for selectively locking said armsindependently to said disk in desired angular positions, an elementprojecting from each of said arms between said shaft and switches inposition to actuate said switches on feed of said carriage to positionscorresponding to the angular settings of said arms relative to saiddisk, and means controlled by the actuation of one or the other of saidswitches depending upon whether rough or finish grinding is to beeffected to slow the action of said feeding means.

3. In combination, a work support and a grinding wheel support, one ofsaid supports comprising a movable carriage, means for moving saidcarriage to produce feed and retracting motions between a wheel on saidwheel support and work on said work support, means including a pair ofindependently adjustable slow speed controls selectively made operativeor inoperative for controlling the speed of such carriage motion in feeddirection, means effective when said carriage reaches independentlyselectable positions in feed direction to render a correspondingly slowspeed control effective for the remainder of such feed motion and meansautomatically controlling said carriage moving means to retract thecarriage on the completion of each such feed motion.

4. In combination, a work support and a grinding wheel support, one ofsaid supports compris ing a movable carriage, means for moving saidcarriage to produce feed and retracting motions between a wheel on saidwheel support and work on said work support, means including a pair ofindependently adjustable slow speed controls selectively made operativeor inoperativ for controlling the speed of such carriage motion in feeddirection, means effective when said carriage reaches independentlyselectable positions in feed direction to render a correspondingly slowspeed control efiective for the remainder of such feed motion, and meansfor selecting said controls alternately.

5. In combination, a work support and a grinding wheel support, one ofsaid supports comprising a movable carriage, means for moving saidcarriage to produce feed and retracting motions between a wheel on saidwheel support and work on said work support, hydraulically actuatedmeans for moving said carriage to relatively feed and retract said wheeland work, a pair of independently adjustable flow limiting elements,means actuated automatically when said carriage reaches a predeterminedposition short of contact between the wheel and work when moving infeeding direction from a starting position during a rough grindingoperation to interpose one of said elements into the hydraulic circuitwith said vworking-speed and for interposing said other element at-,another predetermined position of said carriage short of contact betweenthewheel and work during the next feed which is a-finish grindingfeed ofsaid carriage from said starting posi- :tion'to reduce the rate of feedto finish grinding iieedspeed.

- 6. In combination, a Work support and a grinding-wheel support, meansfor relatively moving said Supports to cause a wheel on said wheel sup-,porhto ,move relatively axially to work on said work-1 support into andout of overlapping relation therewith and to traverse the Work, means orrelatively moving said supports transverse to .saidaxial motion to feedsaid wheel relative to :the work-first at arapid rate from a retractedposition toward the work and then at a slower rate into feeding contactand working feed, and

means for delaying the initiation of said rapid feed after the start ofrelative motion ofasaid wheel and work from retracted to overlappingrelation to insure such overlapping relationbefore said wheel contactsthe work.

THOR H. LJUNGGREN.

WILLIS F MOORE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,673,078 Kempton et al. June 12,1928 1,682,672 Guild Aug. 28, 1928 1,682,673 Taylor Aug. 28, 19281,949,511 Flygare Mar. 6, 1934 2,113,367 Belden et al. Apr. 5, 1938

